Vulcanization of rubber



Patented Sept. 13, 1938 UNITED STATES? PATENT." OFEtl-CEZ VULOANIZATION OF- RUBBER William-E.:Messer,- Cheshire, Conn assignor to.-.

United States Rubber Products,- Inc., New 1 York, N.. Y.; a corporation of.Delaware No- Drawingr Application February: 16,; 1935;-

Serial .No. (k807i 2 Claims.

This invention relates to the use of new and improved accelerator combinations, useful in the production of vulcanized rubber goods.

An object of this invention is to provide a new 5 activator for organic accelerators and more particularly for thiazyl sulphide vulcanization accelerators such as the arylene thiazyl sulphides and disulphides which when used in conjunction therewith will tend to produce less scorching and better calendering as well as better ageing rubber stocks.

These activators are characterized in being broadly amino thiophenols characterized by the grouping 20 wherein R, is hydrogen or a substituted element or group. Examples are o-amino thiophenol, o-o' diamino-diphenyl disulphide, o-o diaminodiphenyl monosulphide, p-amino thiophenol, p-p diamino-diphenyl monosulphide, m-amino thio- 25 phenol, m.m-diamino-diphenyl disulphide,

m.m'-diamino diphenyl monosulphide, o-p-diamino diphenyl disulphide, o-p-diamino diphenyl sulphide and halogen and or alkyl nuclear-substituted derivatives thereof. The salts 30 and acyl derivatives of the amino thiophenols may also be used, as where the hydrogen of the sulfhydryl group is replaced by metal or an acyl group.

The following example is given to illustrate 35 preferred aspects of the invention and is not to be construed as limiting thereof. The parts given are parts by Weight. T stands for tensile in pounds per square inch at break, and E stands for percent elongation at break. The stock that Scorch test (5 pounds per sq. in. steam pressure) Cure in minutes Unaged Cure in ruins. at 30 lbs. sq. in. steam pressure 168 hrs. in oxygen bomb (300 oxygen maintained at 60 C.)

It will be observed that the initial cure, shown by the scorch test, is retarded by use the combination in B. Also that the optimum cure is reached at about the same time as with the full amount of mercaptobenzothiazole (stock A) which shows that an economy in use of the thiazole accelerator may be obtained by the present invention and further with an improvement in ageing properties.

Instead of mercaptobenzothiazole, its disulphide, mercapto-benzo-thiazole-disulphide benzothiazyl disulphide) may be used, as well as other well known thiazole accelerators which are derivatives, substitution products or salts of mercaptobenzothiazole illustrated by dinitro phenyl ester of mercaptobenzothiazole, benzoyl benzothiazyl sulphide, etc.

The amount of activator usable may vary from that specifically shown. Generally it is usable in the same proportions as prior art activators of organic accelerators. The term rubber is to be construed broadly as including caoutchouc, balata, gutta percha, rubber isomers, synthetic rub-- her, and is applicable to latex whether naturally occurring or artificially preferred.

The activators may be used with different types of stock than that illustrated, with other compounding ingredients and other proportions of ingredients. In the case of white stocks the activator is substantially non-discoloring which is another attribute of this invention.

Having thus described my invention, what I claim and desire to protect by Letters Patent is:

l. A process of producing vulcanized rubber goods which comprises accelerating the vulcanization of a vulcanizable rubber stock with an arylene thiazyl sulphide accelerator and an added amount of an activator therefor having the general formula which the proportion of the diphenyl sulphide preponderates over the proportion of the sulphide accelerator.

WILLIAM E. MESSER. 

